Batteries are being used ever more frequently for powering electric vehicles for on-the-road use, as well as for industrial vehicles, such as forklift trucks. Water-filling or "topping-up" systems have been employed for replenishing the water supply in each cell of the battery for the vehicle. The use of such a system enables a decrease in the time and expense as compared to manual battery maintenance operations.
However, in such water-filling systems, the cells of a battery are interconnected by tubes or conduits through which the water flows. Such connections can give rise to a problem in that the hydrogen gas, which oftentimes evolves during operation of the battery, does not readily vent into the atmosphere, as it would in the absence of the interconnecting tubes. A highly explosive hydrogen/air mixture can be formed at a cell. Ignition of the mixture at one cell, by an accidental static discharge or for any other reason, can cause an explosion. The explosive shock wave, traveling through the tubes, can initiate hydrogen/air explosions at other positions along the conduits, thereby causing damage to other ones of the interconnected cells.
Therefore, it would be highly desirable to have an improved battery water-filling system which greatly reduces the hazard of multiple cell damage caused by an accidental hydrogen explosion at one cell. It would be further desirable to have such a system which is inexpensive to make and which is simple to install and to operate.